SEATTLE -- It didn't take long for the top-seeded Seattle Storm to get their first test of the WNBA playoffs.

Looking for their first playoff win since 2012 as they hosted Game 1 of their best-of-five WNBA semifinal matchup with Phoenix, the Storm saw a lead as large as 16 in the third quarter dwindle to two when Mercury center Brittney Griner scored on a putback with 1 minute, 40 seconds remaining.

Could the young Storm, only two of whom were on the roster back in 2012 (Sue Bird and Alysha Clark), hold off an experienced Mercury team looking to replicate Thursday's comeback win at Connecticut that sent them to the semifinals?

In the end, Seattle made the necessary plays to pass the test. A Natasha Howard offensive rebound on the Storm's subsequent possession gave the team another chance to score and Jewell Loyd took advantage with an off-balance jumper to extend the lead to four. Neither team scored again as Seattle held on for the 91-87 victory to take a 1-0 series lead.

"We just didn't stop," Storm star Breanna Stewart said. "We didn't freeze when things got tight. Playing Phoenix, you know that they are always in the game. No matter if it's a two-point game or a 10-point game, they have the opportunity to come back and win. We made some hustle plays that gave us multiple possessions, especially the one where Jewell hit that big shot. That was huge."

Breanna Stewart, who was named MVP earlier Sunday, looked the part, hitting five 3-pointers in the first half and finishing with a game-high 28 points. AP Photo/Elaine Thompson

Loyd took center stage in the fourth quarter as the Mercury were able to cut down on the turnovers that had allowed Seattle to get out in transition in the third quarter and turn a four-point halftime lead into a double-digit edge. Without those easy buckets, the Storm's half-court offense ground down and needed Loyd to create one-on-one with the shot clock winding down. Loyd scored seven of Seattle's 12 points in the final period.

"Everybody sees the shots she made," Storm coach Dan Hughes said. "What I'm going to appreciate is what she did before she took the shot because on both of those she created rhythm and she created space on the pin [screen]. What she did before precipitated the finish. That's just a young player evolving and knowing how to put herself in the best situations when the game is on the line."

League MVP Breanna Stewart scored 19 of her 28 points in the first half, Jewell Loyd added 23 -- including Seattle's final seven points -- and the Storm held on to beat the Phoenix Mercury 91-87 on Sunday in Game 1 of their WNBA semifinal series.

In turn, Loyd pointed to the team's ability to win without shooting well in the fourth quarter, when Seattle shot 5-of-19 (26.3 percent). Six offensive rebounds in the period helped the Storm take time off the clock, and the team came up with a crucial stop on the possession after Loyd's score to all but seal the victory.

"We've played like that all year," Loyd said. "We've been learning how to win off our defense. That is something that we have been focusing on, and going into this game we knew that was going to be key."

The slow-paced final five minutes were a totally different game than the up-tempo, back-and-forth first half that saw neither team lead by more than seven points. Phoenix and Seattle combined to make 18 3-pointers at a 51 percent clip before halftime, each cracking the 50-point barrier.

Awarded the WNBA's MVP trophy before the game, Stewart looked every bit the part. She hit five of the Storm's 10 first-half 3-pointers, scoring 19 points on just 10 shot attempts. Yet Seattle led by just four at the break, thanks in large part to DeWanna Bonner playing the entire first half and scoring 17 points.

The Storm started the third quarter with a Stewart free throw courtesy of a Taurasi technical foul whistled when she marched toward referee Kurt Walker after the halftime buzzer. Taurasi said after the game that she was going to talk to a teammate, but the referees saw it differently and gave her a T.

The freebie started a 13-2 run for Seattle, which benefited from five Mercury turnovers in the half's first 4:15. Suddenly, a Phoenix team playing its third playoff game in six days with a pair of cross-country trips in between found itself on the ropes.

"That was a crucial moment in the game," said Taurasi, who scored 25 points and handed out six assists but was responsible for six of Phoenix's 16 giveaways. "It could have easily gotten away from us. This Seattle team is tough; they have so many weapons. They can separate at any minute. I think we showed a lot of fight and poise. We didn't see as much of that throughout the game as we would have liked, starting with me. The bench did a great job of bringing the force to pull us back in it."

Now that the Mercury are in a five-game series rather than the pair of single-elimination games they won to get here, they can take something from giving the Storm a test on an afternoon when Griner dealt with foul trouble and was limited to 13 points, her lowest playoff output since the 2016 semifinals against Minnesota.

"It makes me feel good going into the next game that we were only one rebound, only four points away," Bonner said. "We will just go, watch a little film and come back."

If the first game was any indication, we're in for a hard-fought series between Phoenix and Seattle continuing with Game 2 on Tuesday (ESPN2, 10 p.m. ET) at KeyArena. But on a day for the Storm to celebrate -- in addition to Stewart's MVP, Howard received Most Improved Player honors and Bird was chosen the winner of the Kim Perrot Sportsmanship Award for the third time in her career -- a Seattle team with limited playoff experience successfully dealt with the first of many new scenarios to come this postseason.